And finally tonight, every four years, abc news brings you a personal portrait of the presidential candidates. Tomorrow night, governor romney, but tonight, president obama. And the talk in the oval office before the storm, by the way. We begin this interview, though, four years ago, before the election, when I surprised the then-candidate, by creating a mock photo of his future as it might be. I have to say, I have fewer grey hairs than I anticipated. Reporter: But as we know, that desk is exactly where he ended up, and he was right about the grey hair. Every morning, do you have something you say to yourself, or -- you're not a ritual kind of -- you know, this walk never gets old. It always reminds you of what incredible opportunities you have to do something that's going to make a difference in people's lives. Reporter: This unlikely president who credits the strong women in his life, his grandmother that tried to work her way up at a bank, and his single mother who taught him, in this world, anything is possible for any child. My biggest regret is that she never got to meet her She would just gobble them up. Reporter: She died of cancer and never saw her son win an election. And what would his father think, the charismatic economist from kenya, who was also an alcoholic who abandoned his son. You wrote in the book, "every man is trying to live up to his father's expectations or make up for his father's mistakes." Yeah. Reporter: For you, both? Both, yeah. That's probably why, you know, my family is so important to me. Reporter: And in the oval office, behind the historic, resolute desk, his favorite pictures, including his wife michelle, who grew up in sma rooms on the top floor of a house in chicago's south side, a working class family, who managed to send their daughter to princeton. This one, I think, captures the three ladies pretty well. It seems like yesterday that i could hold them in my lap. Now, it gets a little harder. Since malia's like 5'9." Reporter: Who's going to teach her to drive? She has expressed great concern about that. We're going to have to figure out the logistics of that, but i promised her that she will, in fact, be able to learn how to drive. Reporter: And on the wall in the oval office, a portrait he requested. He says it is a humbling presence. It's a good reminder having him up on the wall, that this job's not supposed to be easy. And whatever it is that you may be weighed down with, it doesn't come close to comparing to what he had to struggle with. Reporter: Have you thought of what you would say to any new president coming into your office? The only thing you carry into this office is a moral compass. And if you start making decisions based on what's politically convenient at the time, you will be lost.

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